1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "build/build_config.h"
6
7 #if defined(OS_WIN)
8 #include <windows.h>
9 #endif
10 #include <stack>
11
12 #include "base/atomic_sequence_num.h"
13 #include "base/lazy_instance.h"
14 #include "base/logging.h"
15 #include "base/synchronization/waitable_event.h"
16 #include "ipc/ipc_sync_message.h"
17
18 namespace {
19
20 struct WaitableEventLazyInstanceTraits
21 : public base::DefaultLazyInstanceTraits<base::WaitableEvent> {
New__anon59af08500111::WaitableEventLazyInstanceTraits22 static base::WaitableEvent* New(void* instance) {
23 // Use placement new to initialize our instance in our preallocated space.
24 return new (instance) base::WaitableEvent(true, true);
25 }
26 };
27
28 base::LazyInstance<base::WaitableEvent, WaitableEventLazyInstanceTraits>
29 dummy_event = LAZY_INSTANCE_INITIALIZER;
30
31 base::StaticAtomicSequenceNumber g_next_id;
32
33 } // namespace
34
35 namespace IPC {
36
37 #define kSyncMessageHeaderSize 4
38
SyncMessage(int32 routing_id,uint32 type,PriorityValue priority,MessageReplyDeserializer * deserializer)39 SyncMessage::SyncMessage(
40 int32 routing_id,
41 uint32 type,
42 PriorityValue priority,
43 MessageReplyDeserializer* deserializer)
44 : Message(routing_id, type, priority),
45 deserializer_(deserializer),
46 pump_messages_event_(NULL)
47 {
48 set_sync();
49 set_unblock(true);
50
51 // Add synchronous message data before the message payload.
52 SyncHeader header;
53 header.message_id = g_next_id.GetNext();
54 WriteSyncHeader(this, header);
55 }
56
~SyncMessage()57 SyncMessage::~SyncMessage() {
58 }
59
GetReplyDeserializer()60 MessageReplyDeserializer* SyncMessage::GetReplyDeserializer() {
61 DCHECK(deserializer_.get());
62 return deserializer_.release();
63 }
64
EnableMessagePumping()65 void SyncMessage::EnableMessagePumping() {
66 DCHECK(!pump_messages_event_);
67 set_pump_messages_event(dummy_event.Pointer());
68 }
69
IsMessageReplyTo(const Message & msg,int request_id)70 bool SyncMessage::IsMessageReplyTo(const Message& msg, int request_id) {
71 if (!msg.is_reply())
72 return false;
73
74 return GetMessageId(msg) == request_id;
75 }
76
GetDataIterator(const Message * msg)77 PickleIterator SyncMessage::GetDataIterator(const Message* msg) {
78 PickleIterator iter(*msg);
79 if (!iter.SkipBytes(kSyncMessageHeaderSize))
80 return PickleIterator();
81 else
82 return iter;
83 }
84
GetMessageId(const Message & msg)85 int SyncMessage::GetMessageId(const Message& msg) {
86 if (!msg.is_sync() && !msg.is_reply())
87 return 0;
88
89 SyncHeader header;
90 if (!ReadSyncHeader(msg, &header))
91 return 0;
92
93 return header.message_id;
94 }
95
GenerateReply(const Message * msg)96 Message* SyncMessage::GenerateReply(const Message* msg) {
97 DCHECK(msg->is_sync());
98
99 Message* reply = new Message(msg->routing_id(), IPC_REPLY_ID,
100 msg->priority());
101 reply->set_reply();
102
103 SyncHeader header;
104
105 // use the same message id, but this time reply bit is set
106 header.message_id = GetMessageId(*msg);
107 WriteSyncHeader(reply, header);
108
109 return reply;
110 }
111
ReadSyncHeader(const Message & msg,SyncHeader * header)112 bool SyncMessage::ReadSyncHeader(const Message& msg, SyncHeader* header) {
113 DCHECK(msg.is_sync() || msg.is_reply());
114
115 PickleIterator iter(msg);
116 bool result = msg.ReadInt(&iter, &header->message_id);
117 if (!result) {
118 NOTREACHED();
119 return false;
120 }
121
122 return true;
123 }
124
WriteSyncHeader(Message * msg,const SyncHeader & header)125 bool SyncMessage::WriteSyncHeader(Message* msg, const SyncHeader& header) {
126 DCHECK(msg->is_sync() || msg->is_reply());
127 DCHECK(msg->payload_size() == 0);
128 bool result = msg->WriteInt(header.message_id);
129 if (!result) {
130 NOTREACHED();
131 return false;
132 }
133
134 // Note: if you add anything here, you need to update kSyncMessageHeaderSize.
135 DCHECK(kSyncMessageHeaderSize == msg->payload_size());
136
137 return true;
138 }
139
140
SerializeOutputParameters(const Message & msg)141 bool MessageReplyDeserializer::SerializeOutputParameters(const Message& msg) {
142 return SerializeOutputParameters(msg, SyncMessage::GetDataIterator(&msg));
143 }
144
145 } // namespace IPC
146